Chem 111 Exam 3 Study Guide

Types of Chemical Reactions

• Double displacement: parts from 2 compounds switch places to make 2 new compounds 

  • Precipitation reaction: results in formation of an insoluble product 

    • Chemical reaction: entire reaction

    • Ionic equation: reactions with compounds separated and with charges (aq)

      • Keep any solids together (s)

    • Net ionic equation: remove spectator ions

  • Acid-Base reactions

    • Acid + metal → hydrogen gas

    • Acid + carbonate → carbon dioxide 

    • Acid + sulfate → gas formation

• Combustion

• Oxidation reduction (redox)

  • Single displacement reactions 

  • Oxidation: loss of electron; oxidation number increases

  • Reduction: gain electrons; oxidation number decreases  

• Thermite reaction

  • Single displacement redox reaction

  • Exothermic; heat released 

Oxidation Numbers

• Oxygen: -2

• Hydrogen: -1

• Lone elements: 0

Energy Units

• Joule: energy required to move 100g up 1 meter

• calorie: energy required to raise temp of 1 g water 1 degree C

  • 1 calorie = 4.184 J

• Calories: food calories

  • 1 Cal = 1000 cal

Energy

• Exothermic: heat released (delta H -)

  • Ex: freezing water

• Endothermic: heat absorbed (delta H +)

  • Ex: melting ice

• Enthalpy: heat changes at a constant pressure

Math

• M = mol/L

pH

• pH 7 → moles H+ (acid)  = moles of OH- (base)